CHEYENNE WELLS — Colorado’s southeastern plains, still brown from winter and drought, are a long way from the Middle East, but when the Iran war bottled up exports from the Persian Gulf, a resource beneath those prairies became more valuable. It isn’t oil. It’s helium. The closure of the Strait of Hormuz cut off 30% of the world’s helium supply from Qatar. International industrial gas companies, such as France’s Air Liquide and Ireland-based Linde, declared a force majeure and began rationing helium among their customers. The major remaining supply, indeed the world’s largest source is the U.S. The country produces about 44% of the world’s helium, with the best reserves stretching roughly from the Texas Panhandle through Colorado and Wyoming into Canada. And so, on a June morning at the Ladder Creek Helium Plant, just outside Cheyenne Wells, specially designed Air Liquide trailers filled with liquid helium were bound for China, France, Japan, Germany and Austria. “It is an international market, there is a lot of demand for helium and it’s growing,” said Darin Dickey, co-owner Tumbleweed Midstream, which runs the plant. After hydrogen, helium — a colorless, odorless, nontoxic gas — is the second most abundant and lightest element in the universe. A quarter of the sun is helium. It is a small atom, lighter than air. The gas is inert so it does not combine with other elements. It is unique among all the elements in that it can reach ultra-cold temperatures, approaching absolute zero. Here on Earth, it is widely distributed but only in a few strata is it found in concentrations above 2% making it profitable to harvest. The concentrations in southeastern Colorado reach up to 7%, Dickey said. As a result of its unique properties the demand for helium has soared. Magnetic resonance imaging machines,